Presser lifting mechanism for sewing machines



Jan. 20, 1953 ZE|ER 2,625,895

PRESSER LIFTING MECHANISM FOR SEWING MACHINES Filed Nov. 50, 1951 4 Sheets-Sheet l Jmxmlirb grederia 5536 is? WW I 33; WWW OWW Jan. 20, 1953 F. F. ZEIER 2,625,895

PRESSER LIFTING MECHANISM FOR SEWING MACHINES 4 Sheets-Sheet 2 Filed Nov. 30, 1951 Jan. 20, 1953 F. F. ZEIER 2,625,895

PRESSER LIFTING MECHANISM FOR SEWING MACHINES Filed Nov. 30, 1951 4 Sheets-Sheet 5 Frederid Jfeier Jan. 20, 1953 ZEIER PRESSER LIFTING MECHANISM FOR SEWING MACHINES 4 Sheets-Sheet 4 Filed NOV. 50, 1951 rederie fi geier Patented Jan. 20, 1953 PRESSER LIFTING MECHANISM FOR SEWING MACHINES Frederick F. Zeier, Stratfield, Conn., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application November 30, 1951, Serial No. 259,260

Claims.

This invention relates to sewing machines and, more particularly, to sewing machines having an upper four-motion feeding mechanism and an automatic presser-foot lifting mechanism, commonly referred to as an alternating presser. A machine of the type in ouestion is disclosed in my U. S. Patents Nos. 2428.762 and 2,430 440 granted October 7, 1947, and November 4, 1947, respectively.

In such machines, the work is advanced past the stitching instrumentalities usually by means of a four-motion lower feed-dog, a four-motion upper feed-dog and an alternating presser; the upper feed-dog and the alternating presser being spring-biased downwardly into opposed workengaging relation with the lower feed-dog and the cloth-plate, respectively. In order to provide an effective work-feeding condition between the opposed work-engaging surfaces of the feed-dogs and the alternating presser device for all the different speeds of operation of the machine, the upper feed-dog and presser device are yieldin-gly urged downwardly by a rather strong spring, of which the pressure exerted thereby is adjusted in direct proportion to the speed of operation of the machine.

It is the primary object of the present invention toprovide a simplified manually operated mechanism for overcoming this rather heavy spring pressure, whereby the upper feed-dog and presser may be conveniently elevated for the introduction and removal of work from the machine. v Another object of the present invention is to provide a presser lifting mechanism having components relatively proportioned and positioned such that a small expenditure of effort by the operator will overcome the strong spring pressure and elevate the upper feed-dog and presser.

The invention both in structure and in operation, as well as to additional objects thereof, will be best understood from the following description taken in coniunction with the accompanying drawings in which:

Fig. 1 represents a rear side elevation of a sewing machine in which the present invention is incorporated.

Fig. 2 represents a left end elevation of a sewing machine, showing the stitching and feeding mechanisms, with the bed and work-supporting plate in section, and with the needle in its uppermost position.

Fig. 3 represents an enlarged vertical sectional view taken substantially along the lin 3-3, Fig. 1, illustrating the drive for the vibratory frame in which is journaled the needle-bar and the upper feeding-footcarrying bar. 1

Fig. 4 represents a top plan view of a portion of the bracket-arm of the machine with part of the casting broken away to expose the eccentric drives for the vibratory needle-bar frame and the lift of the upper feed-dog.

Fig. 5 represents an enlarged horizontal sec:- tional view taken substantially along the line 55, Fig. 2. x

Fig. 6 represents an enlarged vertical sectional view taken substantially along the line 6-45, Fig. 2. 1

Fig. '7 represents an enlarged horizontal sectional view taken substantially along the line 1'|, Fig. 2.

Fig. 8 represents a vertical sectional view taken substantially along the line 8-8, Fig. 2. J

Referring to the drawings, the invention is em bodied in a sewing machine having a frame comprising a bed H from one end of which rises a standard i2 of an overhanging bracket-arm I3 terminating in a head l4. Journaled for rotation within this frame is a mainor arm-shaft I5 carrying at its outer end the usual belt-driven balance-wheel l6 and at its inner end a counterbalanced needle-bar actuating crank IT. The armshaft l5 has secured to it a belt-pulley l8 connected by a clip-belt l9 to a be1t-pulley 20 fast upon the outer end of a bed-shaft 2| journaled for rotation in the bed H, the ratio between the shafts l5 and 2| being one-to-one.

Actuated by the bed-shaft 2| is the conventional lower four-motion feed-dog 22, and the looper mechanism including a thread-carrying chain-stitch looper 23. For the sake of brevity, a detailed description of the four -motion feeding mechanism will not be given herein, inasmuch as the same is fully described in my U.S. Patent No. 2,292,258, August 4., 1942. With regard to the looper mechanism disclosed in the drawings, it will suflice to say that the looper 23 is preferably of the two-motion type having loopseizing and. -shedding movements only in the line of feed, the looper advancing to seize the needle-thread-loop in a direction opposed to the direction of feed.

Referring now to the mechanism within the machine-head it, it will be seen in Figs. 2 and 8 that the needle-bar actuating crank H has pivotally connected to it the upper end of a needle-v bar actuating link 24 suitably fastened at its lower end to a vertical reciprocatory needle-bar 25 carrying a needle 26.v The needleeb-ar 25 is ournaled in bearings provided in the vertically spaced arms 21 and 2c of a substantially C- shaped needle-bar-fram 23 having a horizontally projecting fulcrum-rod 3G journaled in an extended lug 3| formed integral with the machine-head M.

In the machine illustrated, the needle 26 is moved sidewise in the direction .of movement of the lower four-motion feed-dog 22 in order to assist the feed-dog in advancing the work. This sidewise movement is obtained through the oscillation of the needle-bar-frame 23 about the axis of the fulcrum-rod 30, the oscillations being derived through mechanism comprising a rearwardly and upwardly curved rock-lever 32 (Fig. 3) preferably clamped at its lower end by screws 33 upon the end-portion of the fulcrum-rod 30. At its upper end the rock-jlever 32 is connected by a relatively short pitman 34 (Fig. 4) to a common form of adjustable eccentric 35 secured to rotate with the arm-shaft [5, the adjustable eccentric shown being constructed substantially in accordance with that forming the subject of the U. 5. Patent of W. Myers, No. 2,128,031, granted August 23, 1938. From the foregoing, it will be unders'tood that :as the arm-shaft I is rotated the eccentric 35 actuates the 'pitman 34 which in turn operates the rock-lever-32 to oscillate the -need1e bar'frame 29 about the axis of the fulicrumrodtw. The extent of oscillatory movement imparted to the needle-bar-frame is dependent :upon :t-he amount of eccentricity of the eccentric 35 which can be readily regulated .so that the sidewise movements of the needle are timed with the work-feeding movements of the lower feed- :clokg 22. For .a more complete understanding of the above described needle-bar reciprocating and :vibrating mechanism reference may be made to my U. S. Patent'No. 2,329,681, September 1-4, 1943.

,Gooperatingwith the -lower four motion feedwdoglll is :an upper four-motion feed-dog 35 and apresserfoot'fl. The-upperfeed-dog 36 has imparted to it work-advance andreturn movements dn'athe :line of feed, :aS well as rising and falling movements, all synchronized with the motions of the lower feed-dog .22. The upper feed-dog 33 iscarriedon the lower end of a feed-bar 38 verti- ..c& y 'sli'dable in an elongated bearing lug 39 integ-raliwith the needle-bar-frame 29. Obviously, the upper feed-bar 38 will move sidewise in the line .of teed in unison with the needle since the needle-bar '25 :and the feed-bar 38 are :journaled in the same frame 2-9. The presser-foot 3'! does not have any sidewise movement, but is confined toi-move upanddown relative to the work-support and .in pmpertimed relation with the upper and lower feed-dogs .22 and 36. The presser-foot3! is secured to the lower .end of a, presser-bar 43 journaled for vertical reciprocation in .fixed bushings provided in the machine-head l4. As shown in Figs. 2 and 7, the presser-bar 40, adjacent its upper end, has clamped upon it a guide-bracket M bifurcated at one .end .to straddle a flat-sided guide-rod 42 fixed in the machine-head 14, the bracket 41 and guide-rod 42 functioning to prevent turning of the ,presser-bar 40 in its supporting bushings.

The mechanism for alternately raising and lowering the upper feed-dog 36 and presser-foot 31 is 'best shown Figs. 1, 2 and 5, and comprises a rocking lifting lever 43 freely journaled on a fulcrum-stud 44 fixed in the machine-head [4. The lifting lever at one .end is suitably connected to a stud 45 (Figs. '2 and .5) provided in a head 46 attached to the upper end of the feed-bar 3B. The .head 45 is formed with opposed guide-cheeks 4! which contact the parallel side faces of the lifting lever 43 and constrain the feed-bar 38 from turning in its bearing 33. Journaled in the lifting lever 43 is a stud-shaft 48 formed at one end with a presser-bar lifting arm 49 entering at its free end into a transverse slot 50 (Fig. 5) formed in the presser-bar 4'0. Clamped to the other end of the stud-shaft 43 is a rock-arm 5! connected by a link 52 to a, rock-lever 53 which is provided or otherwise secured to a feed-lift rock-shaft 54 journaled in spaced bearing lugs '55 caston or otherwise attached to the bracketarm 13. At its inner end the feed-lift rock-shaft 54 has clamped upon it a short rock-arm 56 connected by a pitman 5'? to a feed-lift eccentric 38, constructed like eccentric 35 so that its eccentricity may be regulated and thereby the lift of the feed-dog 35 and the presser-foot 3! con trolled.

The feed-dog 33 and presser-foot 3'! are yield- .inly maintained downwardly in work-clamping relation with the lower feed-dog .22 and worksupport, respectively, by means of a :spring arrangement comprising a relatively stiff :blademember '53 which bears at its outer end on a steelball Bilmaintained in position on top of the lifting lever 43 by a retainer'fil attached to the lifting lever. Adjacent its outer end, the blademember 59 underlies a stationary fulcrum edge 62 formed on a'fulc-rum-blockfiz' and at its inner end is connected to a :plunger 63 'slidable withina cylindrical housing 64 containing a coilspring which exerts an upward pull on the blade-member 59 causing the blade-member to .pivot at the fulcrum-edge 62 and force the upper feed-dog 33 and presser-foot 3-! downwardly. Tension exerted by the coil-spring v65 is regulated by turning thehousing-64 which causesthe screw 56 to travel in the lug 6?! and thereby more or .less compress'the coil-spring 65.

For a complete understandingof the manner in which the above described upper four-motion feed and presser mechanism-s function so that the upper feed-dog 35 and presser-foot 31 are alter- 'na-tely raised and lowered and the upper feeddog is additionally moved in the line of feed in unison-with the lower feed-dog '22, reference may .be had to my U. -S. Patent No. 2,428,762, issued October 7, 1947. Suiii'ce it to say that with the parts in the posit-ion shown in Fig. 2, in which the presser-foot 31 is in its lowered or work-engaging position and the feed-dog 36 is in itselevated position and moving to the right, clockwise rotation of the arm-shaft I5 will impart a clockwise turning movement to the feed-lift rock-shaft 54 which will cause the link 52 to move downwardly and turn the stud-shaft 48 through the rock-arm 5!, in a counterclockwise direction within the lifting lever 43. counterclockwise turning of the stud-shaft 48 will cause the free end of the presser-bar lifting arm 49 to pivot on the presser-bar 35], resulting in a lowering of the lifting device 43 about its fulcrum 44 and the consequent lowering of the feed-bar (38 until the feed-dog 36 contacts the work. When this occurs the feed-bar 38 ceases in its downward movement and thus the lifting lever 43 is held stationary, following which continued turning of the feed-lift rock-shaft 54 will cause further counterclockwise motion of the lifting arm 49 resulting in a raising of the presser-bar 40 and the presserfoot 31 off the work. With the presser-foot 31 in elevated position and the upper feed-dog 36 in its lowered or work-engaging position, the feedadvance movement of the upper feed-dog is timed to coincide with the feed-advance movement of the lower feed-dog 22. Thus, the work is clamped between two feed-dogs which are moved simultaneously to positively advance the work.

At the end of the feeding stroke the presserfoot 31 is lowered to clamp the work upon the cloth-plate while the two feed-dogs are moved apart to release the work prior to their return to again start their feed-advance movement. As fully explained in my above mentioned Patent No. 2,428,762, the presser-foot 31 is lowered into its work-engaging position by counterclockwise turning of the feed-lift rock-shaft 54 which, through members 53, 52, 5|, 48 and 46, lowers the presser-bar 46 until the presser-foot 31 engages the work. The presser-bar 46 then becomes the fulcrum for the lifting arm 48 and continued counterclockwise turning of the rock-shaft 54 pivots the lifting lever 43 about its fulcrum 44 and thereby raises the feed-bar 38 and the feeddog 36.

It will be appreciated that both the upper feeddog 36 and presser-foot 31 are yieldingly biased downwardly into work-engaging position by means of the s ring arrangement including the blade-member 58 and coil-spring 65. The present invention is directed specifically to a simplified means for elevating the feed-dog 36 and/or presser-foot 31 against the necessary heavy pressure of this spring arrangement. Referring particularly to Figs. 1, 6 and '1, it will be seen that pivoted at 66 on the machine-head I4 is a bellcrank lever 69 having one of its limbs disposed to underlie the lifting lever 43 adjacent its connection with the feed-bar 38 and its other limb in contact with a cam 16 fixed on one end of a pivot-shaft 1| iournaled in the fulcrum-block 62'; the bell-crank lever being biased into a continuous contact with the cam 16 by a tension spring 12. Brazed or otherwise secured to the other end of the pivot-shaft 1| is an upstanding rock-lever 13 connected at its upper end by a link 14 to a bell-crank lever 15 pivoted at 16 to the bracket-arm l3 and connected by a chain 11 to a suitable manually operated knee-sh ft or treadle device (not shown). A tension spring 18 acting between the bell-crank lever 15 and the bracket-arm of the machine functions to influence the rock-lever 13 against a stop 19 which determines the normally inoperative position of the cam 16. To provide for releasing the tension on the needle-thread when the feeding-foot and presser-foot are raised, the bell-crank lever 15 is equ p ed with a tension-releasing cam-member 86 which is disposed to engage the usual tension releasing plunger 8| of the tension device 82 when the bell-crank lever 15 is rocked on its pivot 16.

The operation of the feeding-foot and presserfoot lifting mechanism is as follows: Manual operation of the knee-shift or treadle device will turn the bell-crank lever 15 in a counterclockwise direction (Fig. 1) causing the link 14 to pull the rock-lever 13 in the same direction. This turns the pivot-shaft 68 in a direction (clockwise in Fig. 6) to cause the cam 16 to pivot the bellcrank lever 69 so that it engage the lifting lever 43 and raises it on its fulcrum 44 in opposition to the spring 65. The lifting lever 43, through its connections with the feed-bar 38 and presserbar 46, effects a rise of the feeding-foot 36 and presser-foot 31. It will be understood that when the feeding-foot and presser-foot are raised, the blade-member 59 pivots on the fulcrum-edge 62 withdrawing the plunger 63 from the housing 64 and compressing the spring 65. When the kneeshift or treadle is released, the pring 65 returns the feeding-foot 36 and Presser-foot 31 to their lowered or operative position.

From the foregoing it will be understood that the present invention contemplates a simple yet very effective mechanism whereby .the upper feeding-foot and presser-foot of a sewing machine can be readily raised regardless of the amount of spring pressure exerted on these elements to maintain them in contact with the work. The use of the cam 16 and bell-crank lever 68 when considered in connection with the relative location of these parts provides a mechanism which requires only a small expenditure of effort on the operators part to overcome the strong spring pressure used to bias the upper feeding-foot and presser-foot into proper work-engaging position. It will be appreciated from the showing in Fig. 6 that the blade-member 59 extends between the pivot-shaft 1i and the pivotal axis 68 of the bellcrank lever 69, and that the fulcrum 62 also is located between the levels of the pivot-shaft axis and the pivotal axis 68. This arrangement makes for a compact mechanism of simple construction free of distortion and capable of being readily assembled and disassembled.

Having thus set forth the nature of the invention, what I claim herein is:

l. The combination in a sewing machine having a frame including a work-support, a reoiprocatory presser-foot carrying bar, a lifting lever movably supported on said frame, operative connections between said lifting lever and said presser-foot carrying bar, spring means for biasing said presser-foot carrying bar toward said work-support, a second lever pivotally mounted on said frame and having one end underlying said lifting lever, a cam rotatably supported on said frame and disposed to engage the other end of said second lever, and manually actuated connections associated with said cam for turning the same to raise the presser-foot carrying bar against the action of said spring means.

2. The combination in a sewing machine having a frame including a work-support, a reciprocatory presser-foot carrying bar, a lifting lever pivotally supported on said frame to swing on a fixed axis, operative connections between said lifting lever and said presser-foot carrying bar, spring means for biasing said presser-foot carrying bar toward said work-support, a second lever pivotally mounted on said frame on an axis disposed transversely of the axis of said lifting lever and having one of its ends underlying said lifting lever, a cam rotatably supported on said frame and arranged to engage the other endportion of said second lever, and manually actuated connections associated with said cam for turning the same to raise the presser-foot carrying bar against the action of said spring means.

3. The combination in a sewing machine having a frame including a work-support and a head overhanging said work-support, a reciprocatory presser-foot carrying bar journaled in said head, a lifting lever pivotally supported on said head to swing on a fixed axis, operative connections between said lifting lever and said presserfoot carrying bar, spring means for biasing said presser-foot carrying bar toward said work-support, a second lever pivotally mounted on said head and movable about an axis disposed trans versely of the axis of said lifting lever and having one of its ends underlying said lifting lever, a pivot-shaft journaled in said head and arranged so that its iongitudinal axis substantially parallel with the pivotal axis of said second lever, a *cam element secured on said pivot-shaft and disposed to engage the other end-portion of said second levenandconnections associated with said pivot-shaft for turning the same to cause said cam to turn said second lever and thereby raise said presser-foot carrying bar.

4. In a sewing machine, a frame including a Work-support and a head overhanging said work- 'support, a reciprocatorypresser-foot carrying bar journaled in said head, a lifting lever pivotally supported on said head, operative connections between said lifting lever and said presser-foot carrying bar, spring means for biasing said presserfoot carrying bar toward said work-support including a blade-member and a fulcrum therefor disposed to be contacted by said blade-member "intermediate its ends, a second lever pivotally mounted on a .fixed axis and having one of its ends operatively associated with said lifting lever, .a second-lever-engaging cam mounted on said head to turn about an axis spaced above the axis of said second lever, and actuating connection associated with said cam for turning the same to raise the presser-foot carrying bar against the action of said spring means.

-5. In a sewing machine, a frame including a Work-support and a head overhanging said worksupport, a reciprocatory presser foot carrying bar journaled in said head, a lifting lever pivotally supported on said head to turn about a fixed axis, operative connections between said lifting lever and said presser-foot carrying bar, spring means for biasing said presser-foot carrying bar toward said work-support including a blademember having one of its end in operative engagement with said lifting lever and a spring connected to the other end of said blade-member, a second lever pivotally mounted on said head to move about an axis arranged transversely of the axis of movement of said lifting lever and having one of its ends operatively associated with said lifting lever, a pivot-shaft journaled in said head and :oscillatable about .an axis disposed above the level of and in substantial parallelism foot carrying bar against the action of said spring me ans FREDERICK F. ZE'IER.

No references cited. 

